MATTHEW CONTINETTI: For Whom the Split Screen Tolls.

On the left of television screens around the world, Trump looked like he had just stepped off the 2020 campaign trail. On the right, Biden looked like a diminished man who is not up to the job and cannot be expected to complete a second full term as president. Biden’s presence confirmed that Robert Hur, the special counsel who investigated the president’s handling of classified documents, was, if anything, pulling punches when he wrote that Biden is “a sympathetic, well-meaning, elderly man with a poor memory.”

The split screen explains why the level of panic among liberal commentators and Democratic strategists on social media was so high during the debate. This wasn’t some “cheapfake” or altered video meme online. This was happening in real time, in a television studio in Atlanta, with only Biden, Trump, Jake Tapper, and Dana Bash in the room. How do you spin what Americans saw Thursday night? You can’t.

Nor were Americans the only ones watching Biden’s performance and assessing Biden’s demeanor. Xi Jinping, Vladimir Putin, the mullahs, and Kim Jong Un tuned in as well. And the world has become a more dangerous place.

How terrible was Biden’s performance? Given how in the tank CNN is, I’m willing to take Burnett at her word here: “He knows every one of these questions is coming” — and he still couldn’t make it through the debate without looking every one of his 181 81 years.